Rasterbasemap

Rasterbasemap is a term used in geographic information systems (GIS) and web mapping to refer to a background map that is composed of raster data. Raster data represents geographic space as a grid of pixels, where each pixel holds a value representing a characteristic of that location, such as color, elevation, or land cover. In the context of a basemap, these pixels typically represent visual information like aerial imagery, satellite imagery, or digitally rendered maps.

Unlike vector basemaps, which use geometric shapes (points, lines, and polygons) to represent features, raster basemaps provide a continuous, image-like representation of the Earth's surface. This makes them ideal for displaying detailed visual context and for providing a photorealistic background for overlaying other GIS data. Common examples of raster basemaps include Google Maps' satellite view, Bing Maps' aerial imagery, and various imagery layers available through GIS data portals.

The use of raster basemaps in web mapping applications allows users to explore geographic areas with high visual fidelity. They are often tiled for efficient loading and display, meaning the raster image is broken down into smaller squares (tiles) that are served to the user as needed, based on their zoom level and geographic extent. This tiling strategy is crucial for managing the large file sizes associated with high-resolution raster imagery. While raster basemaps offer excellent visual detail, they can sometimes be less precise for analytical purposes compared to vector data, as their accuracy is limited by the resolution of the underlying imagery or map.